Wire arc additive manufacturing (WAAM), based on gas metal arc welding, is ideal for fabricating components with sizeable geometries and moderate structural intricacies. However, the electric arc introduces a heat source and directional heat dissipation during deposition, resulting in undesired microstructural characteristics, such as columnar dendritic structures, which lead to variations in hardness across the printed component. Our previous research introduced the friction stir burnishing (FSB) tool integrated with WAAM using a hybrid approach called simultaneous processing. This method suppressed dendrite formation and enhanced the microstructure within WAAM. This approach directly correlates process dynamics, force dynamics, and temperature control, facilitating efficient plastic deformation. This research investigates the relationship between process parameters and microhardness within the combined manufacturing systems of WAAM and FSB tools. The study primarily focuses on using SUS 316L austenitic stainless steel wire material for WAAM and examines how simultaneous operation with the FSB tool impacts microstructure and microhardness. The investigation emphasizes three key parameters: the distance between the welding torch and the FSB tool, tool rotational speed, and machine feed speed. Comprehensive experimentation, including Taguchi analysis, determines optimal values for these parameters. Results indicate that torch-to-tool distance and machine feed speed significantly influence microhardness, while tool rotational speed shows minimal impact. The most effective combination for enhancing microhardness was a torch-to-tool distance of 20 mm, a machine feed speed of 528 mm/min, and a tool rotational speed of 1900 rpm. This combination induced a plastic deformation transformation effect, contributing to the overall improvement in microhardness. Additionally, the optimal parameters for achieving a smaller grain size were a torch-to-tool distance of 17 mm, a machine feed speed of 356 mm/min, and a tool rotational speed of 1900 rpm, as indicated by the average grain size. Furthermore, this study shows significant improvements in microstructure and hardness within 50–200 µm depth from the surface. Comparative analysis between FSB tool-processed and non-processed samples indicates a 22.51% increase in microhardness, with the grain size of the simultaneous process being 7 µm compared to 11.55 µm. Optimizing the process parameters of simultaneous processing achieves superior microhardness and microstructural refinement. Additionally, it highlights the need for further material development to address challenges associated with tool durability, paving the way for advancements in simultaneous processes.

1. [1] J. L. Z. Li et al., “Review of wire arc additive manufacturing for 3D metal printing,” Int. J. Automation Technol., Vol.13, No.3, pp. 346-353, 2019. https://doi.org/10.20965/ijat.2019.p0346
2. [2] W. Jin et al., “Wire arc additive manufacturing of stainless steels: A review,” Applied Sciences, Vol.10, No.5, Article No.1563, 2020. https://doi.org/10.3390/app10051563
3. [3] X. Chen et al., “Microstructure and mechanical properties of the austenitic stainless steel 316L fabricated by gas metal arc additive manufacturing,” Materials Science and Engineering: A, Vol.703, pp. 567-577, 2017. https://doi.org/10.1016/j.msea.2017.05.024
4. [4] W. Wu et al., “Forming process, microstructure, and mechanical properties of thin-walled 316L stainless steel using speed-cold-welding additive manufacturing,” Metals, Vol.9, No.1, Article No.109, 2019. https://doi.org/10.3390/met9010109
5. [5] C. Yu et al., “Trailing rotating-extrusion-assisted wire arc additive manufacturing of duplex stainless steel,” Science and Technology of Welding and Joining, Vol.27, No.8, pp. 629-637, 2022. https://doi.org/10.1080/13621718.2022.2105993
6. [6] Y. Fu, H. Zhang, G. Wang, and H. Wang, “Investigation of mechanical properties for hybrid deposition and micro-rolling of bainite steel,” J. of Materials Processing Technology, Vol.250, pp. 220-227, 2017. https://doi.org/10.1016/j.jmatprotec.2017.07.023
7. [7] J. R. Hönnige et al., “Control of residual stress and distortion in aluminium wire + arc additive manufacture with rolling,” Additive Manufacturing, Vol.22, pp. 775-783, 2018. https://doi.org/10.1016/j.addma.2018.06.015
8. [8] V. R. Duarte et al., “Hot forging wire and arc additive manufacturing (HF-WAAM),” Additive Manufacturing, Vol.35, Article No.101193, 2020. https://doi.org/10.1016/j.addma.2020.101193
9. [9] D. Yuan et al., “Improvement of the grain structure and mechanical properties of austenitic stainless steel fabricated by laser and wire additive manufacturing assisted with ultrasonic vibration,” Materials Science and Engineering: A, Vol.813, Article No.141177, 2021. https://doi.org/10.1016/j.msea.2021.141177
10. [10] M. Diao et al., “Improving mechanical properties of austenitic stainless steel by the grain refinement in wire and arc additive manufacturing assisted with ultrasonic impact treatment,” Materials Science and Engineering: A, Vol.857, Article No.144044, 2022. https://doi.org/10.1016/j.msea.2022.144044
11. [11] Y. Nakata, T. Abe, and J. Kaneko, “Suppression of anisotropy by wire and arc additive manufacturing with finishing process,” J. of Advanced Mechanical Design, Systems, and Manufacturing, Vol.15, No.6, Article No.21-00267, 2021. https://doi.org/10.1299/jamdsm.2021jamdsm0066
12. [12] M. Dinovitzer, X. Chen, J. Laliberte, X. Huang, and H. Frei, “Effect of wire and arc additive manufacturing (WAAM) process parameters on bead geometry and microstructure,” Additive Manufacturing, Vol.26, pp. 138-146, 2019. https://doi.org/10.1016/j.addma.2018.12.013
13. [13] Y. Zhang, Y. Li, J. Zhong, L. Sun, and T. Meng, “Optimum process parameters of IN718 alloy fabricated by plasma arc additive manufacturing using Taguchi-based grey relational analysis,” Materials Today Communications, Vol.37, Article No.107213, 2023. https://doi.org/10.1016/j.mtcomm.2023.107213
14. [14] A. Motwani, A. Kumar, A. Talekar, and Y. Puri, “Process parameters optimization for cold metal transfer-deposited IN625 single-layer bead features by entropy weightage-assisted grey-based Taguchi analysis,” Proc. of the Institution of Mechanical Engineers, Part E: J. of Process Mechanical Engineering, Vol.238, No.2, pp. 800-809, 2024. https://doi.org/10.1177/09544089221150196
15. [15] C. Zhao et al., “Improving the mechanical properties of Cu-15Ni-8Sn alloys by addition of titanium,” Materials, Vol.10, No.9, Article No.1038, 2017. https://doi.org/10.3390/ma10091038
16. [16] K. Nomura, H. Okuda, T. Sano, and S. Asai, “Simultaneous multipoint emissivity measurement via Zebra-patterned blackbody spray method and application to gas tungsten arc welding process,” J. of Manufacturing Processes, Vol.78, pp. 22-31, 2022. https://doi.org/10.1016/j.jmapro.2022.04.004
17. [17] V.-T. Nguyen et al., “WAAM Technique: Process parameters affecting the mechanical properties and microstructures of low-carbon steel,” Metals, Vol.13, No.5, Article No.873, 2023. https://doi.org/10.3390/met13050873
18. [18] N. Haldar, S. Anand, S. Datta, and A. Das, “Microstructure and mechanical property characterization of wire arc additively manufactured SS308L built part: Study of heat interaction phenomena,” J. of Materials Engineering and Performance, 2023. https://doi.org/10.1007/s11665-023-08926-x
19. [19] D. L. Olson, “Prediction of austenitic weld metal microstructure and properties,” Welding Research Supplement, Vol.64, No.10, pp. 281-295, 1985.
20. [20] J. Chen and B. Young, “Stress–strain curves for stainless steel at elevated temperatures,” Engineering Structures, Vol.28, No.2, pp. 229-239, 2006. https://doi.org/10.1016/j.engstruct.2005.07.005
21. [21] B. P. Nagasai, S. Malarvizhi, and V. Balasubramanian, “Mechanical properties and microstructural characteristics of wire arc additive manufactured 308L stainless steel cylindrical components made by gas metal arc and cold metal transfer arc welding processes,” J. of Materials Processing Technology, Vol.307, Article No.117655, 2022. https://doi.org/10.1016/j.jmatprotec.2022.117655
22. [22] S. S. Kumar, N. Murugan, and K. K. Ramachandran, “Microstructure and mechanical properties of friction stir welded AISI 316L austenitic stainless steel joints,” J. of Materials Processing Technology, Vol.254, pp. 79-90, 2018. https://doi.org/10.1016/j.jmatprotec.2017.11.015